|Ron Gray||11/03/2018 12:59:21|
|702 forum posts|
@Levanter - 4 strokes for me but sidewinders not inverted. I’m sure that the majority of running problems with engines are down to poor tuning, wrong tank positions and incorrect or cheap glow plugs. Having said that, my first hand experience of glow 4 strokes has been with Lasers so I’m spoilt but I have helped fellow club members with their Saitos or ASP or SCs and whilst I’m no expert, problem solving has usually centred around the above.
628 forum posts
Just a few more details to add to the fuselage which is nearing completion as a structure.
Here is the tailplane seat again marked with the centreline. The two strips of balsa are spot glued to the top surface to act as a jig. They stop the seat from going too far down into the fuselage because the glue grabs quickly. It is easy to push down slightly but hard to pull up to make any adjustments.
Here is the seat in place and held tightly together with masking tape.
Here is the finished tail end with the slot for the post of the fin and at F8, the slot to locate the forward end of the fin.
This is a repeat photo to show the importance of having the fuselage square and true before drawing together. This has ensured that the tailplane seat (located by the temporary balsa strips) is exactly level and no sanding or adjustment is necessary.
|157 forum posts|
Great demonstration of a skillful builder sharing tips - very much appreciated
stealing borrowing ideas for my GTC build.
628 forum posts
Thank you ace. I a enjoying every minute of it. Not all plain sailing though as a couple of bloopers will be revealed in due course!
The fuselage is about to be put to one side but a couple things still to do.
Here is the nose block dutifully hollowed out according to Peter's instructions. Notice the arrow pointing down but actually should be pointing up! The slot is to allow fine lead shot to be poured into the block at a later date if required. I don't know whether any nose weight will be required as the four stroke engines weigh a bit more than the SC 15s on the original. They are also mounted a bit further forward having to make room for the rear mounted carburettor. If the tail ends up light I will fit a steerable tail wheel instead of the skid. Anyway I want to glue the nose piece in place and not take it off again to add weight.
The nose block is slightly shorter than drawn because I added a doubler on the front face of F1 as I described earlier.
The roughly blanked out nose piece is now glued on and ready for some profiling. The masking take (a best friend) protects the other surfaces while some aggressive sanding is done with the Permagrit.
The nose block is now profiled but not finished sanded. There is a small allowance to sand off as well as rounding off the corners as I know the second it is finished sanded I will bash it on something so that might as well wait for later. The ends of the planks are now properly protected at least.
The doubler on F1 shows up well in this photo.
|McG 6969||12/03/2018 19:38:55|
1905 forum posts
Very neat build, young man.
I really like the way you're approaching 'possible future' issues.
... or is it 'future possible'... No lo sé...
Edited By McG 6969 on 12/03/2018 19:41:40
628 forum posts
Possible future please. Firstly we hope the issues are only possible and secondly they are in the future so I might get chance to head them off.
628 forum posts
Nearly ready to put the fuselage to one side. There is not a lot of detail on the plan concerning the undercarriage but people familiar with Peter's designs will know the ropes.
The bending is quite straight forward especially if you have a wire bender. Worth every penny. Here is one leg where the left hand end goes into the fuselage and the right hand is the wheel axle. It is not actually drooping like it appears and the illusion is because the gear is raked forward. Always work from one end of the wire and it is best to start with the fuselage end because that has to match with the woodwork. If there are any accumulating errors then it doesn't matter too much if the wheels don't end up in exactly the right spot (within reason) as long as the wire is the same shape from one side to the other. To help get this symmetry, do mark the bend positions on both wires at the same time and you wont be far out. Leave plenty of trimming allowance but here I have been a bit generous at the axle end. Better always to be a bit too long and trim than too short.
There is a difference from the plan and that is the short vertical section inboard of the axle. I though I might fit spats and this will be where they are attached. If I change my mind it won't make any difference but I always have the option.
This is its partner and now it is clear that the undercarriage wires cross the fuselage so the port wheel is anchored on the starboard side and visa versa. This gives the undercarriage some torsion suspension as well as its natural springiness. The bending is not accurate to the last fraction of a degree and some gentle tweaks will be done on final assembly to get the aircraft to sit right and to get the wheel pointing in the right direction staring the toe-in / toe-out discussion all over again. It is quite important to get the first bend accurate as this has to go up into the fuselage and also lie nicely across the fuselage bottom.
Do not that where the wires cross under the fuselage one passes in front of the other. This seems obvious but important to take account of when fitting the supports inside the fuselage.
Here are the support blocks that will support the vertical sections in the fuselage. I find them much easier to fabricate than to drill a solid block. Here offcuts of the wire are used to make the correct gap between two birch ply block of the same thickness. This ply has to be hard and strong to take the reaction. The two blocks are glued to a thinner piece of ply as outright strength is not needed. In this case I have used Lite ply as it is much easier to sand. You will see that there is a wide block and a narrow block. This is to make sure that one wire is further forward than the other by the wire diameter so they can sit side by side under the fuselage.
This photo shows the starboard block glued to the doubler, F3 and a ply base inserted in the lower cross grain sheeting. Very strong and provides accurate alignment.